This invention concerns injection of propane gas into internal combustions engines It is known to inject propane into diesel engines to increase power.
It is also known to use propane or other gaseous fuels as the sole fuel in an internal combustion engine.
In the present inventor's prior patent U.S. Pat. No. 6,422,015, boost pressure levels are used to control injection of propane into a diesel engine and this has proven to be highly successful in improving diesel engine performance.
It is also known to inject propane into a gasoline engine at a constant flow rate as described in U.S. Pat. Nos. 5,408,957 and 5,816,224 but this does not fully realize the potential improvement to fuel economy which can be achieved by propane injection.
In a propane fueled engine it is known to use a drop in pressure in a pitot tube connected to the air intake to control the flow of propane injected into the engine. This mode of control of propane injection results in a sluggish response to the throttle valve operation.
It is the object of the present invention to provide a control for propane injection into gasoline and gaseous fuel spark ignition internal combustion engines which improves engine performance while being relatively simple and trouble free.